Boil 50g sugar and 20ml water in a pan for 2-3 minutes until dissolved.
Whisk 3 egg yolks while gradually drizzling in the hot sugar syrup for 10 minutes.
Fold in whipped cream and banana liqueur, pour into ramekins, and freeze for two hours.
Melt 100g dark chocolate over a bain-marie and set aside to cool slightly.
Whisk 6 egg yolks with 100g sugar until pale and fluffy.
Boil milk and cream, then whisk slowly into the egg mixture.
Cook the custard over low heat until thickened, then allow to cool.
Churn in an ice cream machine and freeze for one hour.
Caramelise 200g sugar in a pan over medium heat for 10 minutes.
Stir in rum and coat banana pieces in the mixture before cooling on a tray.
Serve the turned-out parfait with a piece of banana and a scoop of ice cream.